Spark plug assembly



Aug. 18, 1959 A. c. RUSSELL SPARK, PLUG ASSEMBLY Filed July 9, 1956INVENTOR Anci/few 6.' offe A70/PNE y United States Patent O SPARK PLUGASSEMBLY Andrew C. Russell, Shawnee, Okla. Application July 9, 1956,Serial No. 596,631

2 Claims. (Cl. 313-125) This invention relates generally to the field ofinternal combustion engine components and, more particularly, to animprovement in spark plug assemblies for use with such engines.

The contact portions of a spark plug assembly between which the sparkpasses to provide an ignition source for combustible material within thecylinder or combustion chamber of an engine are subject to progressivepitting, erosion and contamination having a profound effect upon thequality of the spark produced and, therefore, the eiiiciency of theengine, as is well known. With conventional types of spark plugassemblies, such circumstance requires relatively frequent removal ofthe plugs from the engine for cleaning or/and resetting and, even withsuch regular maintenance, the useful life of the conventional plugs areextremely limited by virtue of the fact that all sparking must occurbetween a single, invariable pair of portions of the assembly normallycomprising xed, opposed, hot and grounded contacts. Obviously, suchconventional assemblies permit of only a limited amount of cleaning andreadjustment before they rrr-ust be discarded.

It is the primary object of this invention to provide an improved sparkplug assembly having a longer, over all useful life and adapted forperiodic readjustment as may be required without removal of the assemblyfrom the engine block.

It is another important object of the invention to provide such animproved spark plug assembly `in which one of the pair of contactsurfaces between which the spark is formed, preferably the grounded one,is generally annular and the other of such surfaces is shiftable intodifferent positional relationships with said one surface.

It is another important object of the invention to provide such anassembly wherein the other or hot contact surface may be shiftedrotationally of the one or grounded annular surface in order to utilizedifferent portions of the latter presenting a clean, unpitted area aftera pre-` viously used portion thereof has become pitted or dirty, allwithout removal of the assembly from the engine or the necessity ofcleaning the previously used portion ofv the annular surface.

AIt is another important object of the invention to provide such anassembly wherein the spacing of the two surfaces between which the sparkpasses may be selectively varied without removal of the assembly fromthe engine to provide for optimum sparking and efficiency ofV combustionwithin the engine. Y

. It is another important object of the invention to pro' vide suchimproved spark plug assemblies, which may be manufactured at relativelylow cost and are adapted for use in conventional engines by simplesubstitution thereof f or the conventional spark plug assembliesnormally used in such engines.

Still other important objects of the invention, includingcertainsignificant details of construction, will be p 2,900,546 Patented VAug.1 8, 1,959k

"ice

following descripbroken away and shown in cross section for clarity ofillustration;

Fig. 2 is a bottom plan view of the spark plug asf' sembly of Fig. l;

Fig. 3 is a side elevational view of a modified form of spark plugassembly made in accordance with the invention, parts being broken awayand shown in section for clarity of illustration; and

Fig. 4 is a bottom plan View of the assembly shown in Fig. 3.

Referring first particularly to Figs. 1 and 2 of the accompanyingdrawing, the preferred form of improved spark plug is generallydesignated by the numeral 10. Assembly 10 broadly includes, a two-piece,sectioned, tubular steel shell or casing generally designated 12, anelongated, tubular body of insulating material, such as ceramic orporcelain, generally designated 14 extending into and carried by thecasing 12, an elongated, metal electrode generally designated 16extending through the tube or body 14 and the casing 12, and a lateral,metal extension generally designated 18 on the end of electrode' 16normally disposed within the combustion chamber of an engine, extension18 cooperating with a portion here'- inafter to be identied of thecasing 12 to present opposed surfaces between which the desired sparkmay jump.

In the preferred embodiment of the invention shown in Figs. 1 and 2,effort has been made to maintain they The casing 12 includes an uppersection 26 thrcadably connected as at 28 into a lower section 30 havingadjacent'v its bottom extremity external threads 32 adapted forVscrewing the assembly 10 intothe block of a conven-V` The upper casingtional internal combustion engine. section 26 preferably includes ahexagonal wrench-receiving surface 34, while the lower section 30 maybe: provided with an annular knurled surface 36, as is customary.

The externally flanged portion 22 of body 14 is tightly held betweenupper and lower sections 26 and 30 'off casing 12, as will be clear inFig. 1, an upper sealing ring 3S of resilient material being providedbetween the lowermost extremity of section 26 and body portion 22, and alower sealing ring 40 of resilient material being provided between theupwardly facing, frusto-conical, internal surface 42 of section 30 andbody portionV 22. Such rings 38 and 4'0 effect a gas tight seal betweenthe body 14 and the casing 12 when the section 26 is tightly screwedinto the section 30. Y

Tubular body 14 has an elongated bore 44V extending through portion 20and communicating at its lowermost` end with an aligned bore 46 oflesser diameter. Received'V within the bore 44 is an internally threadedmetal sleeve' 48 extending the length of body portion 20 and having' itslowermost end seated on an internal shoulder at the lower extremity ofbore 44 as at 50. Sleeve 48 is permanently mounted within bore 44 ofbody 14 asby'- press tting or bonding during the manufacture of the,ceramic body 14. Sleeve 48 preferably includes an inf y tegral, annular,external ange 52 at its uppermost endv overlying the upper extremity ofbody portion 20.

Electrode 16 includes an externally threaded intermediate portion 54threadably received within sleeve 48; an externally threaded uppermostportion 56 of lesser diameter extending upwardly out of sleeve 48through a washer 58 and nut 60 thereon and receiving lat its uppermostextremity an internally threaded cable terminal cap 62; and a lowermostexternally smooth, elongated portion 64 extending downwardly fromintermediate portion 54 through the lowermost body portion 24.

, On the lowermost end of electrode portion 64, the electrode 16 isprovided with an L-shaped lateral extension 18 having a laterallyextending leg 66 rigidly interconnected with the electrodeportion 64 asby Welding at 68 and, preferably, a shorter leg 70 extending upwardlytoward a lowermost annular surface 72 presented on the bottom extremityof lower casing section 30. It will be clear to those skilled in the artthat the gap across which the ignition spark passes is that presentedbetween the leg 70 of lateral electrode extension 18 and whateverportion of annular surface 72 of lower casing section 30 is thendirectly opposed by the leg 70 by virtue of the condition of rotation ofthe electrode 16, the hot lead of the ignition system being coupled withcap 62 and the metallic electrode 16 providing a circuit path to the leg70, while the casing section 30, including its surface 72, is groundedby virtue of the connection of casing section 30 with the engine blockby means of threads 32.

. It will be clear that the portion of the casing surface 7&2 utilizedas the grounded part of the spark gap can be changedat will, withoutremoval of the assembly 10 from an engine block, simply by rotation ofthe electrode 16 within the sleeve 48, it being noted vthat theinterconnecting threads of sleeve 48 and intermediate electrode portion54 are preferably of sufficiently fine pitch to cause no material changein spacing between leg 70 of extension 18 and surface 72 of casing 12during a single revolution of the electrode 16 within sleeve 48. It willalso be observed, however, that the intermediate electrode portion 54 issufficiently shorter than the sleeve 48 to permit of the electrode 16being rotated several complete revolutions within the sleeve 48,whereupon the spacing between leg 70 and surface 72 may be controllablyvaried in substantially continuous and, if the pitch of theinterconnecting threads between sleeve 48 and electrode 16 is known,precisely measured amounts.

Once the electrode 16 has been set to its desired position providing anoptimum original or reset relationship between the extension leg 70 andan opposing portion of the casing surface 72, the electrode 16 may bereleasably locked in such position by tightening the locknut 60 uponwasher 58 and flange 52 of sleeve 48. When resetting or readjustment isrequired, the nut 60 may be loosened and the electrode 16 rotated eithera small amount, such as forinstance, /sth revolution, to select a cleanand unpitted portion of surface 72, or rotated several revolutions tochange the spacing between leg 70 and surface 72, then the nut 60 may beretightened to again lock the electrode 16 in its desired position.

Referring now to the modified form of the invention illustrated in Figs.3 and 4, the modified assembly is generally designated by the numeral100 and broadly includes an elongated, tubular, metallic casinggenerally designated 112, an elongated tubular body or sleeve ofceramic, porcelain or other insulating material generally designated114, an elongated, metallic electrode generally designated 116, and alaterally extending contact element generally designated 118.

Y Thecasing 112, although generally approximating the externalappearance of conventional spark plug assemblies, may be integrallyformed as a single unitary piece provided with a generally cylindricalbore 120 having its upper extremity internally threaded as at 122. Thecasing 112 is externally threaded as at 1 24 adjacent its lowerextremity for threadably mounting the assembly 100 in a conventionalengine block, and the casing 112 is further provided at its lowermostend with an annular, grounded sparking surface 126.

The insulating body or sleeve 114 is generally cylindrical, althoughpreferably inwardly tapered as at 128 adjacent its uppermost end. Theelectrode 116 includes an elongated intermediate portion 130 extendingthrough a longitudinal bore 132 in the insulating body 114; anuppermost, externally threaded portion 134 extending through aresilient' sealing and insulating washer 136, a lock nut-138 and into aninternally threaded cable terminal cap 140 received thereon; and alowermost substantially cylindrical ball portion-142 separated from thelowermost end of intermediate portion by an inwardly extending annulargroove 144 presenting an upwardly facing shoulder 146 on the ball 142and an opposed, down- Ywardly facing shoulder 148 on the lower end ofintermediate electrode portion 130. Intermediate electrode portion 130is also provided just below the lower end of insulating body 114 with anintegral outturned annular flanged 150 bearing against a resilientWasher 152 interposed between the flange 150 and the lower end 154 ofbody 114.

Above the body 114, the intermediate electrode portion 130 passesthrough an insulating sleeve 156 having 0n its lowermost extremity anoutturned annular ilange 158 resting upon the upper end 160 of body 114.An externally threaded metallic sleeve 162 provided with suitable toolreceiving indentations 164 in its upper surface circumscribes the sleeve156 and has its lower end bearing against the upper end of body 114.Such metallic sleeve 162 is threadably received by the internal threads122 adjacent the upper extremity of casing 12.

The intermediate portion 130 of electrode 116 is preferably permanentlybonded to the ceramic body 114, although electrode portion 130 may beremovably received within bore 132 of body 114, if desired` lt will beclear that the position of body 114, which is slidably and rotatablyreceived within casing 112 is determined by the dual adjustment of thesleeve 162 and the locknut 138. rl`hus, assuming first that the body 114is bonded to the electrode portion 130, loosening and removal of the cap140, nut 138 and washer 136 will permit insertion of a suitable tool toengage sleeve 162 for rotating the same to raise or lower the upwardlylimiting stop for reciprocatory adjustment of body 114 within casing112. At the same time, the rotational position of the body 114 andelectrode 116 may be adjusted by applying rotative force to the exposedportion 134 of electrode 116. It will be noted that there is preferablysufficient frictional interengagement between the insulating sleeve 156and electrode portion 130 to prevent the body 114 and electrode 116 fromdropping downwardly out of the casing 112 during adjustment of sleeve162, although it will be clear to those skilled in the art that aspecial tool which threads upon electrode portion 134 could be used foradjusting the sleeve 162 while at the same time holding the electrode116. After the sleeve 162 has been set to the desired position, thewasher 136 and nut 138 may be replaced and tightened to hold theelectrode 116 and body 114 in place, by virtue of the holding action ofange 150 and washer 152 upon the lowermost end 154 of body 114.

It will be appreciated that the adjustment just de scribed is the mostradical one to which the assembly 100 would normally ever be subjectedand that same should be necessary only on initial installation when theassembly 100 would likely be disengaged from the engine block and asuitable clearance gauge utilized for establishing the desired initialgap between the surface 126 and a part of the laterally extendingelement 118 hereinafter to be more fully described. For minoradjustments of spacing between the element 118 and surface 126, same maynormally be accomplished, assuming that the ange 158 of sleeve 156 andthe washer 136 are of resilient material as preferred, simply by varyingthe degree of tightening of nut 138 upon threaded electrode portion 134.It will be clear that in this modified embodiment of the invention, theelectrode 116 may be rotated relative to the casing 112 without anychange whatsoever in the spacing between the element 118 and the surface126, since the reciprocatory adjustment of electrode 116 does not dependon its rotated position at all.

The element 118 comprises a substantially spherical shell 166 providedwith a cylindrical opening 168 at its uppermost end of dimensionsadapted to receive the portion 170 of electrode 116 between shoulder 148of electrode portion 130 and shoulder 146 of b'all portion 142. Shell166 also is provided with a plurality of slits 172 spaced around theupper portion thereof to permit a number of uppermost resilient fingers174 thereon, it being observed that it is actually the lingers 174 whichare adapted to fit within the groove 144 of electrode 116. As will beclear from Fig. 3, the shell 166 is adapted for a snap-on fit onto theball portion 142 of electrode 116, with the engagement of lingers 172within groove 144 and between shoulders 146 and 148 preventing anysubstantial shifting of the shell 166 upon the ball 142, other thancomplete removal thereof, except that shell 166 may be rotated about thelongitudinal axis of electrode 116 upon overcoming the rather strongfrictional interengagement between fingers 174 and electrode portion170.

A laterally extending contact element 176 is secured upon the shell 166as by welding at 178 and extends to a position disposing the outermoststretch thereof in spaced, proximate, opposition to the grounded surface126 of casing 112. Although, if desired, a part (not shown) similar tothe leg 70 of the above described extension element 18 could be providedupon the element 118, it has been found that same may be omitted withgood results still being obtained. It will be clear that the element 118may be shifted into opposition with different portions of the groundedcontact surface 126 of casing 112 either in the manner above-mentionedas involving rotation of the entire electrode 116 or by simply removingthe assembly 100 from the engine block and rotating the shell 166 uponball 162 against the strong frictional interengagement between fingers174 and electrode portion 170.

It will be clear to those skilled in the art that the two embodimentsselected for illustrating the principles of the invention could bevaried, modified, or partially combined in a number of ways withoutdeparting from the true spirit and intention of the invention.Accordingly, it is to be understood that the invention should be deemedlimited only by the scope of the claims that follow.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

l. In a spark plug, an elongated, tubular metal casing provided with asubstantially fiat, annular, sparking surface on one end thereof and ina plane substantially perpendicular to the longitudinal axis of thecasing; an elongated, metal electrode extending through said casing andbeyond both ends of the latter; structure mounting said electrode uponsaid casing in electrically insulated relationship to the latter; alaterally extending, metal extension releasably mounted on the end ofthe electrode extending beyond said one end of said casing and having asparking part thereof disposed in spaced, proximate relationship to asegment only of said sparking surface of said casing, said extensionalways being in substantially the same disposition relative to theelectrode longitudinally of the latter; means for shifting saidextension longitudinally relative to said casing Without shifting saidextension rotationally relative to said casing; and means for shiftingsaid electrode rotationally relative to said casing without shiftingsaid electrode longitudinally relative to said casing.

2. In a spark plug as set forth in claim 1, wherein said last mentionedmeans mounts said extension upon said electrode for shiftable relativepositioning thereof rotationally of the electrode without substantiallyaltering the relative positioning of said extension and said electrodelongitudinally of the latter.

References Cited in the tile of this patent UNITED STATES PATENTS1,139,694 Marean May 18, 1915 1,192,602 Bond July 25, 1916 1,211,157Hughes Jan. 2, 1917 1,337,679 Williams Apr. 20, 1920 1,525,707 WetzelFeb. 10, 1925 1,543,628 Stover June 23, 1925 1,691,760 Fox Nov. 13, 19282,195,543 Songer Apr. 2, 1940

